<!DOCTYPE HTML>

<!-- READ BEFORE UPDATING:
If this test is updated make sure to increment the "revision" value of the
associated test in content/test/gpu/gpu_tests/pixel_test_pages.py. This will ensure
that the baseline images are regenerated on the next run.
-->

<html>
<head>
<title>OffscreenCanvas webgl with resizing: red triangle with softened edge.</title>
<style type="text/css">
.nomargin {
  margin: 0px auto;
}
</style>
<script id="myWorker" type="text/worker">
function drawTriangle(gl)
{
  gl.clearColor(0, 1, 0, 1);
  gl.clear(gl.COLOR_BUFFER_BIT);

  var prog = gl.createProgram();
  var vs = gl.createShader(gl.VERTEX_SHADER);
  gl.shaderSource(vs, [
    'attribute vec2 pos;', 'void main() {',
    '  gl_Position = vec4(pos, 0., .5);', '}'
  ].join('\n'));
  gl.compileShader(vs);
  if (!gl.getShaderParameter(vs, gl.COMPILE_STATUS)) {
    throw 'failed to compiled shader';
  }
  gl.attachShader(prog, vs);

  var fs = gl.createShader(gl.FRAGMENT_SHADER);
  gl.shaderSource(
      fs, [ 'void main() {', '  gl_FragColor = vec4(1, 0, 0.5, 1);', '}' ].join('\n'));
  gl.compileShader(fs);
  if (!gl.getShaderParameter(fs, gl.COMPILE_STATUS)) {
    throw 'failed to compiled shader';
  }
  gl.attachShader(prog, fs);

  gl.linkProgram(prog);
  if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
    throw "Could not link the shader program!";
  }
  gl.useProgram(prog);

  gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer());
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([ -.5, .5, 0, 0, -.5, -.5 ]),
                gl.STATIC_DRAW);
  var attr = gl.getAttribLocation(prog, 'pos');
  gl.enableVertexAttribArray(attr);
  gl.vertexAttribPointer(attr, 2, gl.FLOAT, false, 0, 0);

  gl.drawArrays(gl.TRIANGLE_STRIP, 0, 3);
}

self.onmessage = function(e) {
  var transferred = e.data;
  // Resize the canvas from 200X200 to 40X50
  // The triangle should scale proportionately with edge softened
  transferred.width = 40;
  transferred.height = 50;

  var gl = transferred.getContext('webgl');
  drawTriangle(gl);

  self.postMessage("");
};
</script>
<script>
var g_swapsBeforeAck = 15;

function makeWorker(script)
{
   var blob = new Blob([script]);
   return new Worker(URL.createObjectURL(blob));
}

function waitForFinish()
{
  if (g_swapsBeforeAck == 0) {
    domAutomationController.send("SUCCESS");
  } else {
    g_swapsBeforeAck--;
    document.getElementById('container').style.zIndex = g_swapsBeforeAck + 1;
    window.requestAnimationFrame(waitForFinish);
  }
}

function main()
{
  var canvas2D = document.getElementById("c");
  var offscreenCanvas = canvas2D.transferControlToOffscreen();
  var worker = makeWorker(document.getElementById("myWorker").textContent);
  worker.onmessage = function (e) {
      waitForFinish();
  };
  worker.postMessage(offscreenCanvas, [offscreenCanvas]);
}
</script>
</head>
<body onload="main()">
<div style="position:relative; width:200px; height:200px; background-color:white">
</div>
<div id="container" style="position:absolute; top:0px; left:0px">
<canvas id="c" width="200" height="200" class="nomargin"></canvas>
</div>
</body>
</html>
